By Robert McMillan And Josh Beckerman

World-wide shipments of personal computers dropped in the first quarter compared with a year earlier, the ninth such quarterly decline since 2012, according to researcher firm Gartner Inc.

Gartner estimated world-wide PC shipments totaled 71.7 million units, down 5.2% from a year earlier. The Stamford, Conn., firm said a double-digit percentage decline in desktop sales partly was offset by a pickup in sales of notebooks, hybrids and Windows tablets.

The data show the lowest number of PC shipments since the second quarter of 2009, Gartner analyst Mikako Kitagawa said on Thursday. The PC market has been hit hard as corporations slowed the rate at which they refresh employee desktops and consumers increasingly spend their money on tablets and smartphones.

A year ago, Microsoft Corp. stopped supporting its Windows XP operating system giving desktop PC sales a boost. That triggered a round of corporate upgrades as companies bought new systems to continue to qualify for Microsoft support. But this year Gartner expects PC shipments to continue to slip.

"Right now there is not a strong driver for PC growth," Ms. Kitagawa said, although the Gartner report added that the recent decline "is not necessarily a sign of sluggish overall PC sales long term."

International Data Corp., another research company that reported quarterly PC sales on Thursday, said world-wide shipments fell a greater 6.7% to 68.5 million units. The results exceeded its "cautious" forecast, IDC said, but the market "remains heavily dependent on pricing being a major driver." The firm added that demand for higher-priced systems remains "tenuous."

IDC and Gartner's numbers don't match because the two firms disagree over what constitutes a PC. Gartner's figures include premium ultramobiles, but not Chromebook notebooks, Windows tablets with a smaller than 10-inch display or non-Windows tablets. IDC counts Chromebooks and excludes tablets.

Lenovo Group Ltd. kept the top spot in world-wide shipments, while Hewlett-Packard Co--in second place globally--extended its U.S. lead, according to Gartner and IDC. Dell Inc. remained in third place world-wide.

Asustek Computer Inc. edged ahead of Acer Inc. for the fourth spot on Gartner's list. Acer kept the fourth spot on IDC's list, with Asustek surpassing Apple Inc. for fifth place.

Apple finished third in the U.S. on Gartner's list and fourth on IDC's U.S. list.

Gartner said the overall results "support our projection of a moderate decline of PC shipments in 2015, which will lead to a slow, consistent growth stage for the next five years."

Write to Josh Beckerman at josh.beckerman@wsj.com

Access Investor Kit for Lenovo Group Ltd.

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=HK0992009065

Access Investor Kit for Acer, Inc.

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=TW0002353000

Access Investor Kit for Acer, Inc.

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=US0044341065

Access Investor Kit for Apple, Inc.

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=US0378331005

Access Investor Kit for Gartner, Inc.

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=US3666511072

Access Investor Kit for Lenovo Group Ltd.

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=US5262501050

Subscribe to WSJ: http://online.wsj.com?mod=djnwires